relock bootloader

hi guys, today i got notified that there is a new update for my c6602 which is 10.5.a.0.233)
tried to update it via sony pc companion but i got an error because of using modified software (bootloader unlocked)
i tried relocking it via flashtool BLU button but the phone wouldn't boot so i had to unlock it again
is there a working method for relocking it?
thanks

hi guys, today i got notified that there is a new update for my c6602 which is 10.5.a.0.233)
tried to update it via sony pc companion but i got an error because of using modified software (bootloader unlocked)
i tried relocking it via flashtool BLU button but the phone wouldn't boot so i had to unlock it again
is there a working method for relocking it?
thanks

thanks
it worked by using the flash tool to relock the bootloader using the BLU button (but after this the device won't boot)
then i flashed the new FTF file, i got the new firmware and the bootloader locked

thanks
it worked by using the flash tool to relock the bootloader using the BLU button (but after this the device won't boot)
then i flashed the new FTF file, i got the new firmware and the bootloader locked

The bootloader is not relocked when you flash stock FTF.
You will loose custom recovery and root.
Flash recovery and root again.

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